This invention relates to a flexible tube assembly for an endoscope and more particularly to a type adapted for medical treatment by emitting X-rays in conjunction with diagnosis by the endoscope. An endoscope for observing and photographing the inner walls of the body cavity consists of an observation section positioned at the forward end of a flexible tube assembly inserted into the body cavity and a control section fitted to the rear end of said flexible tube assembly exposed outside of the body and provided with an eyepiece for observation. The flexible tube assembly further includes a glass fiber member for image transmission, another glass fiber member for illumination of affected parts of the body, a passageway through which to conduct a clamp, an angle wire for allowing the bending of the forward end portion of said flexible tube assembly and a flexible sheath concentrically surrounding the core tube.
Where observation is made of the inner walls of the body cavity, the flexible tube assembly is inserted thereinto and light is emitted through the illumination glass fiber member to light up affected parts being observed. Reflections from the affected parts pass through an observation window, object lens and image transmission glass fiber member to concentrate the image of said affected parts at the rear end face of the glass fiber member. Said image is observed through the object lens of an eyepiece.
Such is the general application of an endoscope. In recent years, however, there has come to be practised medical treatment by emitting X-rays in conjunction with diagnosis by the endoscope. Where X-rays are irradiated to affected parts, the forward end portion of the flexible tube assembly inserted into the body is naturally exposed to said X-rays. At this time, the glass fiber members included in the flexible tube assembly are stained yellow by X-rays, resulting in a prominent decrease in their transparency.
It is accordingly the object of this invention to provide a flexible tube assembly for an endoscope capable of preventing the glass fiber members from being stained yellow by X-rays even when they are emitted in conjunction with the observation of the body cavity walls.